{
语法百题 解题报告：
 http://git.oschina.net/et0662/sznoi-grammar/ 
}
var
	x,n:double;
	i:integer=1;
begin
	readln(x);
	n:=13;
	x:=1+(x/100);
	while (x*n)<20 do
	begin
		n:=x*n;
		inc(i);
	end;
	writeln(i);
end.
